What Is the Difference Between Mercon & Dexron Automatic Transmission Fluids?

by Teshia Washington
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Automatic transmissions require fluid to lubricate the interior components. Driving conditions generate heat in the transmission. Automatic transmission fluid cools the transmission components and allows for smooth transfer of power to the transmission for proper function. Different car makes and models require various types of automatic transmission fluid. Two common types are Dexron and Mercon.


Mercon entered the market in 1987, according to the book "The Role of the Chemist in Automotive Design" by Herman K. Phlegm. This automatic transmission fluid type ceased production in 2007. Mercon is used in Ford vehicles and is not compatible with Ford and Toyota's type F fluid. After 2007, vehicles using Mercon can be filled with Mercon V. Mercon V was introduced in 1997 for use in the Ranger, Explorer, Aerostar and other Ford vehicles. Though similar to Dexron in its red color, there are a few differences chemically. Mercon has a different flash point from Dexron. Mercon has a flash point of 170 degrees Fahrenheit and a fire point of 185 degrees.


Dexron is used in General Motors vehicles. It was released in 1994 and was created to increase fuel efficiency and reduce emissions, according to Volume 1 of the book "Fuels and Lubricants Handbook: Technology, Properties, Performance and Testing." Dextron III was developed to facilitate smoother shifting and reduce oxidation while maintaining lower temperatures. Originally Dexron used sperm whale oil in its composition.The government outlawed the importation of the sperm whale oil in 1971. Later it was reformulated and released sans sperm whale oil and with enhanced rust and corrosion inhibitors. Its flash point is 177 degrees, slightly higher than that of Mercon.


Consult the owner's manual for transmission fluid requirements for a specific vehicle. Transmission fluids are different, having been formulated for specific vehicles and having different chemical makeups. Before using a particular type, ensure it is the correct type for the specific vehicle being serviced. Transmission fluid should be added when the fluid is low and at specific intervals. Traditionally, the transmission fluid should be changed every 60,000 to 100,000 miles. Failure to change the fluid at scheduled times can result in a damaged transmission and costly repairs. Regularly check the transmission fluid levels and refill between fluid changes if necessary.

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